1. Field of the Invention
The present invention relates to flowmeters which cause resistors to generate heat, thereby measuring the flow rate of a gas, and more particularly to a gas flowmeter which measures the flow of an exhaust gas flowing through an automobile engine system.
2. Description of the Related Art
As a prior art known example, JP-A-59-136620 discloses a means which includes at least two temperature-dependent resistors disposal in a fluid and at least two bridge circuits connecting the resistors. In use, the two resisters are heated to different temperatures to measure an amount of air necessary for the internal combustion engine. Especially, a flow-sensing resistor element is illustrated as having a structure in which a pair of protective heaters is each disposed at a respective one of both ends of a heat-sensing heating resistor. Both the resistor and the protective heaters are set to the same temperature in use. This prevents transmission of heat from the flow-sensing heating resistors to the substrate. Thus, the responsiveness of the measuring resistors is increased in spite of their masses being large.